Insight: How Torque Sensors Could Produce Closer Racing in IMSA's GT Classes
Sportscar365 goes on a deep-dive with IMSA's Matt Kurdock on the integration of torque sensors to GTD Pro, GTD for this season...
While the 2023 season saw the highly anticipated launch of the GTP class and last year brought an influx of new GT3 machinery as well a new Michelin tire compound, 2025 could arguably be the year of increased competition in the IMSA WeatherTech SportsCar Championship.
But IMSA’s technical team is also hoping the upcoming campaign will produce even closer racing, particularly in the GT classes, amid the integration of torque sensors to the GTD Pro and GTD categories that has taken the paddock by storm.
After dialogue with manufacturers and teams dating back nearly two years, the much anticipated switch to driveshaft-equipped sensors, instead of air restrictors and boost controls that previously regulated each cars’ power output, is now a reality in the production-based classes.
It hasn’t come without some controversy, mainly related to the increased costs for teams, but IMSA is hoping it’s the right price to pay to deliver more equitable racing between its nine different GT3 manufacturers in the WeatherTech Championship.
According to IMSA’s managing director of engineering Matt Kurdock, the timing was right to make the same kind of step forward as it and the FIA and ACO did with torque sensors in the GTP and FIA World Endurance Championship Hypercar classes several years ago.
"We have two years of experience with them in the GTP class and based on everything we've seen and how they operate, how we're able to regulate the competition with the sensors, and how we're able to use the sensor data to help maintain the Balance of Performance process, we felt that all those benefits we could see in GTP were worth the investment to expand into GTD Pro and GTD for 2025,” says Kurdock.
First introduced to GT3-based machinery in the WEC and European Le Mans Series’ LMGT3 class last year, IMSA is utilizing the same MagCanica-developed sensors for its GT categories, with only minor differences between the two series, such as data loggers. WEC, for instance, uses Marelli loggers where IMSA relies upon Bosch units.
Kurdock indicates that it’s been a relatively seamless process for GT3 manufacturers that were in WEC/ELMS competition last year, along with those that have had two-plus years of experience with either LMDh or LMH-based machinery as well.
Eight of the nine GT3 manufacturers — all but Mercedes-AMG — were on the WEC LMGT3 grid in 2024.
"One thing we get to leverage is that we have an open dialogue with our colleagues at the FIA and ACO regarding how the torque sensors have been used in both Hypercar and GTP,” says Kurdock. “They've been able to share a lot of information with how they were used in LMGT3 as well.
"We've been able to align on control methodologies, regulation control. The mechanisms we use in GTP in terms of how we look at both torque sensors on the car and how we look at the engine speed sensor and use those to basically run what we call an integral on the car. That allows the teams and the manufacturers using the car to understand how close they are to the prescribed limit at any engine speed and gives them some tolerance to run up against up that limit.
"We've shared the same control methodology that we have in GTP in GTD. It allows, not only IMSA to use the same tools we built up in our software that we run on the Bosch data loggers and the post-processing we do, but it also allows those manufacturers involved in both championships to leverage what they've put together."